The present invention concerns a mechanism which, starting with a set of parts in bulk, enables those parts to be oriented and dispensed while preserving an orientation that can vary according to the application in question. More particularly, this mechanism is designed for the automatic orientation and dispensing of parts that have an offset center of gravity with respect to the middle of their length. As an example of such parts, mascara brushes could be cited, since their relatively heavy handle causes an offset of the center of gravity.
In general, in the industry the orientation and dispensing of parts is currently accomplished by means of vibrating bowl devices, or by means of blade feeders. These devices are not entirely satisfactory. In particular, they present risks of mechanical jamming, they do not allow orientation with complete reliability, they risk damaging the surface condition of fragile parts, and they have rather limited rates of dispensing. Moreover, current devices only accept parts of very specific dimensions, and they can not be adapted to parts of various sizes without major adjustment or modifications.
The present invention seeks to eliminate these disadvantages by furnishing, for parts of the type considered here, a particularly reliable orientation and dispensing mechanism that ensures a high rate of dispensing and is suitable for dispensing parts of variable dimensions with a minimum of adjustment, while preventing damage to said parts.
To that end, an essential object of the invention is a mechanism for the automatic orientation and dispensing of parts that have an offset center of gravity with respect to the middle of their length, this mechanism having essentially, in combination:
a first endless chain, extending in a vertical or oblique plane, with a horizontal upper strand, this first endless chain bearing cups distributed evenly over its full length, each cup having a receptacle suitable for receiving one part,
a second endless chain, extending in a plane perpendicular to that of the first endless chain, the second endless chain bearing moving guides distributed evenly over its full length, with the same spacing as the above-mentioned cups, the moving guides passing above the cups of the upper strand of the first endless chain being situated to correspond with the intervals between the receptacles of these cups,
synchronized, motorized drive means for these two endless chains, and
means to feed the parts onto said chains, and means to guide the descent by gravity of said parts, feeding them to meet the moving guides before they fall into the receptacles of the cups of the upper strand of the first endless chain.
Thus a mechanism is produced that is capable of continuously processing parts to be oriented, starting from a stock of parts in bulk, a small quantity of parts being processed simultaneously. These parts are first emptied onto the mechanism per se, by the feeding means which, in particular, can be accomplished in the form of a blade feeder of a known type, which lifts the parts from a bulk storage hopper and releases them with a horizontal pre-orientation. The parts thus released fall, or slide on a steeply inclined plane, first to meet the moving guides, then to end their fall in the receptacles of the cups, where these parts are held in the xe2x80x9cuprightxe2x80x9d position. In this way the parts are oriented because when they reach the tops of the moving guides, they tip over because for the most part their center of gravity is downward.
An appropriate configuration and distribution of the moving guides borne by the second endless chain ensure an effective orientation process.
Advantageously, these moving guides include guides of different heights, preferably all having at their upper end a point having two lateral faces of opposite pitch. According to one particular embodiment, these moving guides include guides of three different heights:
high guides, distributed along the second endless chain at intervals equal to four times the intervals of the cups carried by the first endless chain,
guides of medium height, which also are distributed at intervals equal to four times the intervals of the cups, and attached to the second endless chain in the middle of the intervals separating the high guides, and
low guides, distributed according to a spacing equal to or twice that of the intervals of the cups, and attached to the second endless chain in the intervals defined between the preceding high and medium height guides.
Preferably, the interval between two consecutive high guides is greater than the length of the parts to be oriented, in order to prevent these parts from becoming wedged between the guides, thus ensuring that they fall into the cups.
Moreover, the moving guides carried by the second endless chain are advantageously made of a plastic material in order not to damage the parts that fall on the points of the guides.
The operation of the mechanism for automatic orientation and selection of parts covered by the invention requires perfect synchronization of the drive of the two endless chains, in such a way as to maintain the intervals between the moving guides in correspondence with the receptacles of the cups located on the upper strand of the first chain, and thus to ensure that the parts fall all the way to the bottom of the cups. According to a particular embodiment of the invention, the synchronized motorized drive means of the two endless chains, bearing respectively the cups and the moving guides, are composed of a reducer motor coupled to a drive wheel around which the first endless chain, bearing cups, passes, while a ring and pinion transmission device connects the shaft of one of the drive or idler wheels of the first endless chain to a pinion gear around which the second endless chain, bearing the moving guides, passes.
It will be noted that the two endless chains are not necessarily of the same length. Advantageously, the upper horizontal strand of the first endless chain, bearing the cups, is extended beyond the second endless chain, bearing the moving guides, in the direction of movement of the cups. Thus, the moving guides retract at a certain point, while the cups continue their horizontal course on the upper strand of the first endless chain, forming a zone in which the parts that are improperly oriented in the cups (a small number of parts, but some nonetheless) can be automatically evacuated simply by their tipping over under the effect of gravity, their center of gravity being offset toward the top.
Beyond that zone of tipping and evacuation of improperly oriented parts, fixed guides are advantageously provided which enclose the first endless chain and its cups around one of the drive or idler wheels, and along a portion of its lower strand, to ensure that the properly oriented parts are held until a point of release where these oriented parts can be taken over by other transfer or processing means outside the orientation and selection mechanism.
On the whole, the invention enables an orientation and selection mechanism to be obtained that is compact, makes it possible to simultaneously process a small quantity of parts, using the principle of continuous transport which permits processing rates that are not achieved, or are poorly controlled, by current devices. Thus, the mechanism according to the invention can process between 60 and 150 parts per minute (depending on the parts to be dispensed).
Provided the moving guides are made of plastic, the mechanism covered by the invention also makes it possible to protect the surface condition and any decorations the processed parts may have. Thus, this mechanism can dispense fragile parts, such as finished parts or subassemblies to be used in filling, assembly or packaging.
The mechanism covered by the invention is also able to dispense parts of the same family, but having significant geometric and/or dimensional variations from one part to another. This can be done with a minimum of adjustments, with or without change of set-up, such as the set-up of the cups.